We are studying slowly adapting joint receptors in the medial articular nerve (MAN) of the cat using simultaneous multiunit recording techniques. We plan to obtain joint receptor population responses to natural movements such as walking, trotting and galloping from unanesthetized animals. We will use analysis of covariance of the multiple-unit data to determine how homogenous the joint receptor population is. Our objective is to obtain a quantitative description of the responses of all active joint receptors in the medial articular nerve to a broad class of natural movements. We want to find answers to the following two questions: First: Is it possible to determine joint angle during a natural movement from the information provided by the joint receptors in the MAN? and second: What are optimal ways of pooling joint receptor afferents to provide a measure of joint angle? In addition we hope to refine presently available techniques for chronic peripheral nerve recording and we hope to refine methods for isolation of single units from multiple-unit records. Data will be obtained from cats by placing two specially designed chronic electrode sets around the MAN. The neural response and joint angle will be recorded while the cat walks on a treadmill at different speeds to produce different gaits. Data will be collected from a single animal for up to a two week period. Bayesian stastical analysis will be used to determine the probability density function of joint angle conditioned on composite measures of neural response. We will find composite measures of neural response by applying factor analysis to the neural population data.